QgraphicsScene & openGL, which can be the best approach to mix both ?

I'm going to start my vectorial viewer app develop.
I have explored the 2D and 3D QT tools and I have the impression that I have to create two independents data worlds.
The Qgrapchicsscene needs 'items', the opengl needs raw data ....
What is your opinion ? QML 3D ¿

There are examples available on how to mix them. A bit of googling will bring them on your screen. From the top of my head, they use a QGLWidget as the viewport widget for a QGraphicsView, and then leverage QGraphicsView::drawBackground or ::drawForeground to render GL stuff into that viewport while layering the graphics items on top.